1. Field of the Invention
The present invention generally relates to the field of semiconductor power devices, and more particularly, to a super-junction semiconductor power device with various gate arrangements and a fabrication method thereof.
2. Description of the Prior Art
A power device is used in power management; for example, in a switching power supply, a management integrated circuit in the core or peripheral region of a computer, a backlight power supply or in an electric motor control. The types of power devices include insulated gate bipolar transistors (IGBT), metal-oxide-semiconductor field effect transistors (MOSFET), and bipolar junction transistors (BJT), among which the MOSFETs are the most widely applied because of their energy saving properties and their ability to provide faster switching speeds.
In one kind of power MOSFET device, two kind of epitaxial layers, one with a first conductivity type and the other one with a second conductivity type, are disposed alternatively to form several PN junctions inside a body. The junctions are orthogonal to a surface of the body and the device with such PN junctions is also called a super-junction power MOSFET device. In addition, in order to control the on-off state of current transmitting in devices, a plurality of gate structure units is disposed on a cell region of the device. But in a conventional super-junction power device, some drawbacks still need to be overcome. For example, each of the gate structure units usually has non-rounded corner, which may reduce the voltage sustaining ability of the device. In addition, this kind of gate structure unit layout is not good enough to meet the requirement of various products.
In light of the above, there is still a need for providing a structure and a method for fabricating an improved super-junction power MOSFET, which has to be capable of overcoming the shortcomings and deficiencies of the prior art.